Properties of dense matter in a supernova core in the relativistic mean-field theory

We have used the Zimanyi & Moszkowski model in the relativistic mean-field theory to study the properties of asymmetric nuclear matter and the equation of state (EOS) for supernova matter. We find that even though muons are included in the chemical composition of neutron-star matter, this model still results in a small proton concentration so that only themodified Urca process occurs as a main neutrino reaction in neutron stars. This conclusion is opposite to that of the previous studies in the relativistic mean-field theory. The incompressibility of symmetric nuclearmatter is consistent with both the experimental values extracted from the nuclear physics and the constraints placed on the EOS by observations of neutron star masses. If the EOS for supernovamatter is described by thismodel, the prompt mechanism for Type II supervovae cannot work, but the EOS is likely to be favourable to the delayed explosion mechanism.